A chimeric α-amylase engineered from Bacillus acidicola and Geobacillus thermoleovorans with improved thermostability and catalytic efficiency. (1st April 2016)

• Record Type: Journal Article
• Authors: Parashar, Deepak; Satyanarayana, T
• Is Part Of: Journal of industrial microbiology & biotechnology. Volume 43:Number 4(2016)
• Page Start: 473
• Page End: 484
• Publication Date: 2016-04-01
• Subjects: Chimeric α-amylase -- Thermostability -- Acid stability -- Catalytic efficiency -- Raw starch; Industrial microbiology -- Periodicals; 660.62
• DOI: 10.1007/s10295-015-1721-7
• Languages: English
• ISSNs: 1367-5435

Abstract

Abstract: The α-amylase (Ba-amy) of Bacillus acidicola was fused with DNA fragments encoding partial N- and C-terminal region of thermostable α-amylase gene of Geobacillus thermoleovorans ( Gt - amy ). The chimeric enzyme (Ba-Gt-amy) expressed in Escherichia coli displays marked increase in catalytic efficiency [ K cat : 4 × 10 4 s −1 and K cat / K m : 5 × 10 4 mL −1 mg −1 s −1 ] and higher thermostability than Ba-amy. The melting temperature ( T m ) of Ba-Gt-amy (73.8 °C) is also higher than Ba-amy (62 °C), and the CD spectrum analysis revealed the stability of the former, despite minor alteration in secondary structure. Langmuir–Hinshelwood kinetic analysis suggests that the adsorption of Ba-Gt-amy onto raw starch is more favourable than Ba-amy. Ba-Gt-amy is thus a suitable biocatalyst for raw starch saccharification at sub-gelatinization temperatures because of its acid stability, thermostability and Ca 2+ independence, and better than the other known bacterial acidic α-amylases.